152 PRACTICAL COURSE IN BOTANY 
bane and bitterweed (Heleniwm 
tenuifolium), illustrate this relation. 
On the other hand, when the leaves 
are large and rounded in outline, as 
those of the sunflower, hollyhock, and 
catalpa, they are usually separated 
by longer internodes, or their blades 
are cut and incised so that the sun- 
light easily strikes through to the 
: lower ones. 
Fic. 190.— Narrow leaves 170. Other external characteristics 
dncromitied wertleabaaws. to be observed in leaves are: — 
(1) General Outline: whether round, oval, heart-shaped, 
etc. (Figs. 191-197). 
(2) Margins: whether unbroken (entire), or variously 
toothed and indented. (Figs. 198-202.) 
191 192 193 194 
195 196 
197 
Fias. 191-197. — Shapes of leaves: 191, lanceolate; 192, spatulate; 193, oval; 
194, obovate; 195, kidney-shaped; 196, deltoid; 197, lyrate. (191-195 after Gray.) 
(3) Texture: whether thick, thin, soft, hard, fleshy, 
feathery, brittle. 
(4) Surface: smooth, shining, dull, wrinkled, hairy, or 
otherwise roughened. 
LE 
